The typical pulse duration in diagnostic ultrasound is?

The typical pulse duration in diagnostic ultrasound is?

• A. 3 to 20 microseconds
• B. 0.03 to 0.2 microseconds
• C. 0.3 to 2.0 microseconds
• D. 1 to 10 milliseconds

Answer: (C)

Pulse duration in diagnostic ultrasound is about how long the transmitted burst lasts, and it’s kept very short to improve axial resolution—the ability to separate structures along the beam path. The typical range is 0.3 to 2.0 microseconds, which matches a few cycles of the ultrasound wave at the frequencies used in medical imaging (roughly 2–15 MHz). Because pulse duration equals the number of cycles times the period, higher frequencies have shorter periods, so a brief burst of just a few cycles lands in the microsecond range. Longer bursts would smear echoes from nearby reflectors and blur fine details, while pulses that are too short would lose energy and reduce signal strength. Pulses in milliseconds would be far too long for imaging timing. So the 0.3 to 2.0 microseconds range best reflects how diagnostic ultrasound pulses are actually produced.

Pulse duration in diagnostic ultrasound is about how long the transmitted burst lasts, and it’s kept very short to improve axial resolution—the ability to separate structures along the beam path. The typical range is 0.3 to 2.0 microseconds, which matches a few cycles of the ultrasound wave at the frequencies used in medical imaging (roughly 2–15 MHz). Because pulse duration equals the number of cycles times the period, higher frequencies have shorter periods, so a brief burst of just a few cycles lands in the microsecond range. Longer bursts would smear echoes from nearby reflectors and blur fine details, while pulses that are too short would lose energy and reduce signal strength. Pulses in milliseconds would be far too long for imaging timing. So the 0.3 to 2.0 microseconds range best reflects how diagnostic ultrasound pulses are actually produced.